Sickle cell anemia and thalassemia are the result of genetic defects in adult globin genes. The expression of small amounts of fetal globin have completely prevented clinical disease in these disorders. We have developed a number of drugs including isobutyramide, which increase expression of fetal globin in patients with these disorders. The purpose of this study is to determine if isobutyramide will stimulate fetal hemoglobin in patients with sickle cell anemia and beta thalassemia.